David Friedman and I conducted roughly this discussion online a couple of years ago, tied to the intelligence that the Duke of Wellington (who incidentally owned the two fastest horses in England and, by my estimate, rode them an astonishing 54 miles on the day of Waterloo) paid his farrier 4,500 pounds a year. We agreed on this being roughly $300K.

I can't vouch for the mileage figure, but if it's in the right ballpark, it means you couldn't be Wellington at Waterloo without fabulous horses. And that the Iron Duke had an iron bottom.

Update: This post was reposted at Brad DeLong's blog, where it attracted these comments.